this is the most important

1. ...
Mathematics Facts & Trivia
A 3-digit resultof any number multipliedby 11 has its
middle digitthe sum of othertwo, like:
21 × 11 = 231 (2+1=3)
13 × 11 = 143 (1+3=4)
44 × 11 = 484 (4+4=8)
What type of algebra, in whichlogical operationsare
replacedby symbols,is also known as symboliclogic?
:Boolean
Name the 3rd-century BC Greekmathematician who
wrote ElementsofGeometry,whichremaineda
standard textbookuntil the 19th century
:euclid
1 × 8 + 1 = 9
12 × 8 + 2 = 98
123 × 8 + 3 = 987
1234 × 8 + 4 = 9876
12345 × 8 + 5 = 98765
123456 × 8 + 6 = 987654

2. 9 × 9 + 7 = 88
98 × 9 + 6 = 888
987 × 9 + 5 = 8888
9876 × 9 + 4 = 88888
98765 × 9 + 3 = 888888